Fix #24702: Voice too long corruption

[mathesoncalum]

Resolves: #24702

Introduced with #23911

The idea here is to scan backwards from the input position to find the previous ChordRest, check if the duration overlaps with the input position, and shorten the previous ChordRest by the length of the overlap...

[cbjeukendrup]

It works well when the new duration of the previous note can be represented as a single duration, but otherwise still causes corruptions:

Schermopname.2024-09-28.om.01.54.24.mov

So changeCrLen is unable to split a note into multiple tied notes when it cannot be represented as a single note. There must be some other method somewhere in the engraving module that is able to do this, but I wouldn't know where.

[mathesoncalum]

@cbjeukendrup apparently it can actually split the note into multiple ties, but only if the target ChordRest is being lengthened instead of shortened... Looking into it.